Subterranean drilling operations generally employ a rotary drill bit that is rotated while being advanced through rock formations. Cutting elements or structures affixed to the rotary drill bit cut the rock while drilling fluid removes formation debris and carries it back to the surface. The drilling fluid is pumped from the surface through the drill string and out through one or more (usually a plurality of) nozzles located on the drill bit. The nozzles direct jets or streams of the drilling fluid to clean and cool cutting surfaces of the drill bit and for the aforementioned debris removal.
The number of nozzles on the drill bit depends on the bit size and the arrangement of the cutting elements on the face of the individual drill bit. Accordingly, the total flow area of the nozzles is determined by first evaluating the requirements of hydraulics for the particular drilling application. Moreover, the life of a drill bit having PDC cutting elements is typically extended when it is adequately lubricated and cooled during the drilling process. In contrast, having inadequate fluid flow to the face of a drill bit allows formation cuttings to collect on the faces of the cutting elements. This collection of cuttings isolates the cutting elements from the drilling fluid. This also reduces the rate of penetration of the drill bit and if the debris collection is sufficiently high the cutting elements may overheat which increases the wear rate.
Examples of nozzles for delivering drilling fluids include: U.S. Pat. No. 4,776,412 to Thompson; U.S. Pat. No. 4,794,995 to Matson, et al.; U.S. Pat. No. 5,380,068 to Raghaven; U.S. Pat. Nos. 5,494,124, 5,632,349, and 5,653,298 to Dove et al.; U.S. Pat. No. 6,311,793 to Larsen et al.; U.S. Patent Application No. 2004/0155125 A1 to Kramer et al.; and U.S. Patent Application No. 2004/0069540 A1 to Kriesels.